Thread (24 messages) 24 messages, 5 authors, 2016-11-28

[PATCH 1/7] add binding for stm32 multifunctions timer driver

From: Benjamin Gaignard <hidden>
Date: 2016-11-23 17:02:11
Also in: linux-devicetree, linux-iio, linux-pwm, lkml

2016-11-23 10:21 GMT+01:00 Lee Jones [off-list ref]:
On Wed, 23 Nov 2016, Benjamin Gaignard wrote:
quoted
2016-11-22 17:52 GMT+01:00 Lee Jones [off-list ref]:
quoted
On Tue, 22 Nov 2016, Benjamin Gaignard wrote:
quoted
Add bindings information for stm32 timer MFD

Signed-off-by: Benjamin Gaignard <redacted>
---
 .../devicetree/bindings/mfd/stm32-timer.txt        | 53 ++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mfd/stm32-timer.txt
diff --git a/Documentation/devicetree/bindings/mfd/stm32-timer.txt b/Documentation/devicetree/bindings/mfd/stm32-timer.txt
new file mode 100644
index 0000000..3cefce1
--- /dev/null
+++ b/Documentation/devicetree/bindings/mfd/stm32-timer.txt
@@ -0,0 +1,53 @@
+STM32 multifunctions timer driver
"STM32 Multi-Function Timer/PWM device bindings"

Doesn't this shared device have a better name?
In SoC documentation those hardware blocks are named "advanced-control
timers", "general purpose timers" or "basic timers"
"stm32-timer" name is already used for clock source driver, that why I
have prefix it with mfd
MFD is a Linuxisum and has no place in hardware description.

Please used one of the names you mentioned above.
I will go for "st,stm32-advanced-timer"
Hopefully the one that best fits.
quoted
quoted
quoted
+stm32 timer MFD allow to handle at the same time pwm and IIO timer devices
No need for this sentence.
OK
quoted
quoted
+Required parameters:
+- compatible: must be one of the follow value:
+     "st,stm32-mfd-timer1"
+     "st,stm32-mfd-timer2"
+     "st,stm32-mfd-timer3"
+     "st,stm32-mfd-timer4"
+     "st,stm32-mfd-timer5"
+     "st,stm32-mfd-timer6"
+     "st,stm32-mfd-timer7"
+     "st,stm32-mfd-timer8"
+     "st,stm32-mfd-timer9"
+     "st,stm32-mfd-timer10"
+     "st,stm32-mfd-timer11"
+     "st,stm32-mfd-timer12"
+     "st,stm32-mfd-timer13"
+     "st,stm32-mfd-timer14"
We don't normally number devices.

What's stopping you from simply doing:

        pwm1: pwm1 at 40010000 {
                compatible = "st,stm32-pwm";
        };
        pwm2: pwm1 at 40020000 {
                compatible = "st,stm32-pwm";
        };
        pwm3: pwm1 at 40030000 {
                compatible = "st,stm32-pwm";
        };
Because each instance of the hardware is slightly different: number of
pwm channels, triggers capabilities, etc ..
so I need to distinguish them.
Since it look to be a problem I will follow your suggestion and add a
property this driver to be able to identify each instance.
Do you think that "id" parameter (integer for 1 to 14) is acceptable ?
Unfortunately not. IDs aren't allowed in DT.

What about "pwm-chans" and "trigger"?

pwm-chans              : Number of available channels available
For pwm I need those 4 properties:
st,pwm-number: the number of PWM devices
st,complementary: if exist have complementary ouput
st,32bit-counter: if exist have 32 bits counter
st,breakinput-polarity: if set enable break input feature.

Is it acceptable from pwm maintainer point of view ?
trigger                : Boolean value specifying whether a timer is present
Following our discussion on IRC I will try to code for your proposal:

advanced-timer at 40010000 {
        compatible = "st,stm32-advanced-timer";
        reg = <0x40010000 0x400>;
        clocks = <&rcc 0 160>;
        clock-names = "clk_int";

        pwm at 0 {
                compatible = "st,stm32-pwm";
                st,pwm-number= <4>;
                st,complementary;
                st,breakinput;
        };

        timer at 0 {
                reg = <1>;
                compatible = "st,stm32-iio-timer";
                interrupts = <27>;
                triggers = <5 2 3 4>;
        };
};

triggers parameter will be used to know which trigger are valid for
the IIO device

[snip]
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